Food Structure


The Structural and chemical compositions of digested oat bran were analyzed by fluorescence and other types of light microscopy. The digestion of oat bran was carried out under two conditions - in vitro, by incubation with human saliva, and in vivo, by feeding rats with an oat-bran supplemented diet. Comparison of the digestive breakdown among different structural components of oat bran was conducted by microscopically examining samples obtained from the tents of the large intestine (LIC) of the rats. Results of the examinations revealed that the (1-3) (1-4) - B - D - glucan - rich cell wall of the subaleurone layer, along with its cellular content, were relatively more digestible than the comparable structures of the aleurone layer. Most of the aleurone structural components, including the cell wall and the phytin globoids, as well as the outer fibrous layers of the bran, remained detectable in the ileum samples, indicating that they were poorly digested by the endogenous gastrointestinal enzymes of the rats. Partial to complete degradations of the aleurone cell wall and the phytin globoids were detected in the digested oat bran tissues found in the LIC of the rats. Microscopic examination of the LIC samples also revealed the presence of the rat intestinal microflora, undigested outer tissues of the bran with its detectable phenolic content, and a large amount of crystalline structures that differed morphologically and chemically from oat phytin globaoids. Energy dispersive X-ray microanalysis of the LIC samples revealed their elemental composition to be high in both phosphorus and calcium along with traces of magnesium, potassium and iron.

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